Same entry in the Synagoge, Lexica Segueriana 336.12 and Photius, Lexicon pi595 Theodoridis; and cf. already Hesychius pi1424 and pi1433. The headword must be quoted from somewhere; there are numerous possibilities. For this verb, with a range of literal and figurative applications, see generally LSJ s.v.
Glossing, here, with prau/+nei emphasizes the meaning of becoming soft or mild over that of making or becoming ripe. Contrast pi 1356, which uses pepai/nei along with melani/zei ("blackens") to define perka/zei; again the same entry is found in Photius and elsewhere. Like perka/zw, pepai/nw is often used to describe grapes or figs: Xenophon, Oeconomicus 19.19 (grapes); Theophrastus, Causes of Plants 3.16.3 (grapes); Eratosthenes, Constellations 1.41d.16 = Aristotle fr. 343 (figs); and Hesychius omicron658 (figs).
pepai/nw is also common in medical texts, where it is used to describe tumors (e.g. Rufus, De renum et vesicae morbis 11.1) or an illness reaching its crisis (e.g. Hippocrates, De diaeta in morbis acutis 11; Coa praesagia 148).